AGRONOMIC EFFICIENCY OF REACTIVE ROCK PHOSPHATES FOR CORN PRODUCTION IN BRAZILThe objective of the study was to evaluate the agronomic efficiency of reactive rock phosphates for corn production, in compasion to triple superphosphate. The study was conducted on an Oxisol of medium texture. The rock phosphates were: Arad and Gafsa, applied at 100 and 200 kg P2O5 ha-1; and Marrocco rock phosphate and triple superphosphate, applied at 0, 50, 100, 200 and 400 kg P2O5 ha-1. Arad, Marrocco and Gafsa rock phosphate were calculated to be 60, 80 and 97%, respectively, as effective as triple superphosphate in supplying P to corn. There was positive correlation among the concentration of P in corn leaves and grain yield to estimate the availability of P to corn. The resin soil P test was more precise than Mehlich-1.
Arad; Gafsa; Marroco; phosphorus; resin
